1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 // UNSUPPORTED: c++03, c++11, c++14, c++17
10 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
11 
12 // constexpr iterator(iterator<!Const> i)
13 //             requires Const &&
14 //                      convertible_­to<iterator_t<V>, OuterIter> &&
15 //                      convertible_­to<iterator_t<InnerRng>, InnerIter>;
16 
17 #include <cassert>
18 #include <ranges>
19 
20 #include "test_macros.h"
21 #include "../types.h"
22 
23 using ConstCompatibleInner = BufferView<int*>;
24 
25 using ConstIncompatibleInner = BufferView<forward_iterator<const int*>, forward_iterator<const int*>,
26                                           bidirectional_iterator<int*>, bidirectional_iterator<int*>>;
27 
28 template <class Inner>
29 using ConstCompatibleOuter = BufferView<const Inner*, const Inner*, Inner*, Inner*>;
30 
31 template <class Inner>
32 using ConstIncompatibleOuter = BufferView<forward_iterator<const Inner*>, forward_iterator<const Inner*>,
33                                           bidirectional_iterator<Inner*>, bidirectional_iterator<Inner*>>;
34 
test()35 constexpr bool test() {
36   int buffer[4][4] = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}, {13, 14, 15, 16}};
37   {
38     CopyableChild children[4] = {CopyableChild(buffer[0]), CopyableChild(buffer[1]), CopyableChild(buffer[2]),
39                                  CopyableChild(buffer[3])};
40     std::ranges::join_view jv(CopyableParent{children});
41     auto iter1 = jv.begin();
42     using iterator = decltype(iter1);
43     using const_iterator = decltype(std::as_const(jv).begin());
44     static_assert(!std::is_same_v<iterator, const_iterator>);
45     const_iterator iter2 = iter1;
46     assert(iter1 == iter2);
47 
48     // We cannot create a non-const iterator from a const iterator.
49     static_assert(!std::constructible_from<iterator, const_iterator>);
50   }
51 
52   // !convertible_to<inner_iterator, inner_const_iterator>>;
53   {
54     ConstIncompatibleInner inners[2] = {buffer[0], buffer[1]};
55     ConstCompatibleOuter<ConstIncompatibleInner> outer{inners};
56     std::ranges::join_view jv(outer);
57     using iterator = decltype(jv.begin());
58     using const_iterator = decltype(std::as_const(jv).begin());
59     static_assert(!std::is_same_v<iterator, const_iterator>);
60 
61     static_assert(!std::constructible_from<const_iterator, iterator>);
62     static_assert(!std::constructible_from<iterator, const_iterator>);
63   }
64 
65   // !convertible_to<outer_iterator, outer_const_iterator>>;
66   {
67     ConstCompatibleInner inners[2] = {buffer[0], buffer[1]};
68     ConstIncompatibleOuter<ConstCompatibleInner> outer{inners};
69     std::ranges::join_view jv(outer);
70     using iterator = decltype(jv.begin());
71     using const_iterator = decltype(std::as_const(jv).begin());
72     static_assert(!std::is_same_v<iterator, const_iterator>);
73 
74     static_assert(!std::constructible_from<const_iterator, iterator>);
75     static_assert(!std::constructible_from<iterator, const_iterator>);
76   }
77 
78   return true;
79 }
80 
main(int,char **)81 int main(int, char**) {
82   test();
83   static_assert(test());
84 
85   return 0;
86 }
87